Monolithic protective waterproofing system

ABSTRACT

A monolithic protective waterproofing system for light rail and intermodal class I railroad bridges comprehends a multiple layer product installed in-situ. It includes a sprayed on primer, a sprayed on membrane having a thickness of between 60 and 120 mils, a second sprayed on layer of membrane having a thickness of about 20 mils that is utilized as an adhesive that is rapidly covered with a resilient mat having a thickness of between approximately 6 and 12 mm, a second layer of a sprayed on primer and a top coat of sprayed on membrane of approximately 30 to 50 mils. Both the product and method of installation are disclosed.

FIELD

The present disclosure relates to a waterproofing system for railroad bridge decks and similar structures and more particularly to a monolithic protective waterproofing system or product for light rail and intermodal class I railroad bridges and similar structures and a method of installing same.

BACKGROUND

The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.

As the nation's transportation infrastructure ages, attention is returning to enhancing the service life of existing structures and ensuring that new structures are built with the most modern techniques and materials to provide the maximum attainable service life.

One of the most difficult service environments exists on light rail transit bridges and intermodal class I railroad bridges. Heavy loads, exposure to high humidity and often salt spray and the placement of rock ballast on the bridge deck which supports the railway ties and track all contribute to aging of the structure. The ballast has a particularly deleterious effect on concrete bridge decks as sharp corners and edges of the ballast (which is crushed rock) concentrates loads. What begins as surface cracking and spalling leads to significant deterioration of the concrete as water and often salt flows into the deck itself. Deterioration through the freeze-thaw cycle and corrosion of reinforcing steel in the concrete follow. Even steel bridge decks are not immune from such deterioration as the ballast is capable of puncturing, abrading and wearing even the most rugged deck coatings. Cracks, gouges and discontinuities in a deck coating commence a process of deterioration by rusting.

From this background, it is apparent that materials, systems, products and processes of application which extend the service life of railroad bridges and similar structures are highly desirable. The present invention is so directed.

SUMMARY

The present invention provides a monolithic protective waterproofing system or product for light rail and intermodal class I railroad bridges and similar structures and a method of installing same. The waterproofing system is a multi-layer product installed in-situ on either new structures or structures previously in service. It includes a primer, an elastomeric membrane having a thickness of between approximately 60 and 120 mils, a second layer of elastomeric membrane having a thickness of 20 mils that is utilized as an adhesive that is rapidly covered and upon which is pressed a rubber mat having a thickness of approximately 8 mm, a second layer of a primer and a top coat of elastomeric membrane of between approximately 30 to 50 mils.

Before the various layers are applied to a bridge deck, the deck is cleaned by, for example, sand blasting to remove any loose material such as rust, spalled or damaged concrete, previous coatings and anything that might interfere with achieving a tight and continuous bond between the bridge deck and the product. New bridge decks or recently replaced decks may only require inspection. Then, the first layer of primer is applied and allowed to dry followed by the first layer of membrane which is also allowed to dry. A second, thinner layer of membrane, which functions as an adhesive, is next applied followed quickly by application of adjacent strips of a resilient, preferably rubber, mat. The resilient mat is supplied in rolls of, for example, four or six feet by fifty feet (1.219 or 1.829 meters by 15.24 meters). A second layer of primer is then applied to the top of the resilient mats and a final layer of membrane is sprayed onto the primer and mats, completing the installation process. The track ballast, railroad ties and railroad track are then installed and the bridge is placed in or returned to service.

It is thus an aspect of the present invention to provide a monolithic protective waterproofing product for railroad bridges and the like.

It is a further aspect of the present invention to provide a method of building up a monolithic protective waterproofing product in-situ on a railroad bridge or similar structure.

It is a still further aspect of the present invention to provide a monolithic protective waterproofing product having layers of primer, membrane and resilient mat.

It is a still further aspect of the present invention to provide a monolithic protective waterproofing product having first layers of primer and membrane, a resilient, rubber mat and additional layers of primer and membrane on a railroad bridge or similar structure.

It is a still further aspect of the present invention to provide a method of building up a monolithic protective waterproofing product having layers of primer, membrane and resilient mat on a railroad bridge.

It is a still further aspect of the present invention to provide a method of building up a monolithic protective waterproofing product having first layers of primer and membrane, a resilient, rubber mat and additional layers of primer and membrane on a railroad bridge or similar structure.

Further aspects, advantages and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1 is a perspective view of a light rail bridge or similar structure from which the ballast, railroad ties and railroad track have been removed which is undergoing a cleaning step prior to installation of the waterproofing product of the present invention;

FIG. 2 is a top, plan view of a railroad bridge or similar structure schematically and sequentially showing certain steps of the method of installation of the waterproofing product according to the present invention;

FIG. 3 is a fragmentary, sectional, schematic view illustrating the application of the first layer of primer and the first layer of membrane to the bridge deck;

FIG. 4 is a fragmentary, sectional, schematic view illustrating the application of the second layer of membrane and the resilient mat to the bridge deck;

FIG. 5 is a fragmentary, sectional, schematic view illustrating the application of the second layer of primer and the second layer of membrane to the bridge deck;

FIG. 6 is a greatly enlarged, fragmentary, sectional view of the layers of a monolithic waterproofing product according to the present invention installed on a bridge deck or similar structure; and

FIG. 7 is a flow chart presenting the installation steps of a monolithic waterproofing product according to the present invention, including a bridge deck preparation step.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

With reference to FIG. 1, a railroad bridge or similar structure either new or undergoing updating, repair, refurbishment or rehabilitation is illustrated and generally designated by the reference number 10. The bridge 10 may be disposed across a river or a stream 12 or other obstacle and includes a horizontal deck 14 which may be fabricated of wood, concrete or steel upon which one or multiple railroad tracks 20 are supported and carried. Each railroad track 20 includes ballast (crushed rock) 22 which supports ties 24 which, in turn support and locate the rails 26 of the track 20. Because the bridge 10 is undergoing repair or rehabilitation, the ballast 22, the ties 24 and the rails 26 have been removed from the bridge deck 14, as illustrated.

It will be appreciated that the product 40 and the method of the present invention is intended for and is usable on both new construction and bridges 10 that have been in service and are undergoing updating, repair, refurbishment or rehabilitation. In the latter case, a first or preliminary step to the in-situ installation of the waterproofing product 40 of the present invention is cleaning the bridge deck 14 and removal of any loose material such as rust, spalled or damaged concrete, previous coatings and anything that might interfere with achieving a tight and continuous bond between the bridge deck 14 and the waterproofing product 40. If the bridge deck 14 is concrete and is spalled, pitted or contains other defects, it must be sand blasted or metal shot blasted through the use of conventional sand or metal shot blasting equipment 32 and an operator or technician 34 to remove laitance and other contamination and then patched with a concrete patching material. If the bridge deck 14 is steel it should be prepared similarly to SP 6 or near white. If the bridge deck 14 is new or has been recently replaced, this step may simply involve inspection of the bridge deck surface to ensure its integrity and relative smoothness and cleanliness.

Referring now to FIGS. 2 and 3 and 7, the building up or in-situ installation of the waterproofing product 40 according to the present invention begins with the spraying, squeegeeing or rolling of a first layer of primer 42 onto the bridge deck 14. The first layer of primer 42 is preferably applied at a rate of approximately 130 to 200 square feet per gallon (3.12 to 4.8 square meters per liter) over concrete surfaces and at a rate of approximately 200 to 400 square feet per gallon (4.8 to 9.6 square meters per liter) over steel surfaces. If the bridge deck 14 is steel and has a 5 mil profile or better, i.e., less, use of the first layer of primer 42 is not necessary. The first layer of primer 42 is preferably one of polyurethane, polyurea, methyl methacrylate, a polyurethane hybrid or an acrylic. The first layer of primer 42 is preferably allowed to become tack free before the next step is undertaken.

The first layer or base coat of membrane 44 is then sprayed on the first layer of primer 42 at a rate of approximately 20 square feet per gallon (0.48 square meters per liter) to a minimum thickness of approximately 80 mils and allowed to cure. The thickness of the first layer or base coat of membrane 44 may be increased to 120 mils and even thicker if desired. The first layer of membrane 44 is preferably an elastomer and is one of polyurethane, polyurea, methyl methacrylate, a polyurethane hybrid, bitumen or an acrylic.

Referring now to FIGS. 2, 4, 6 and 7, a second, thinner layer of elastomeric membrane 46 is sprayed onto the surface of the first layer of membrane 44 by an operator or technician 34 just prior to the application of a layer of a resilient mat 50. The resilient mat 50 is unrolled, preferably in closely adjacent transverse or longitudinal strips, on the bridge deck 14. Transverse strips or panels of the resilient mat 50 are illustrated in solid lines in FIG. 2 and longitudinal strips or panels of the resilient mat 50 are illustrated by a phantom line in FIG. 2. The strips or panels of the resilient mat 50 are pressed into position by a cushioned roller 52 on a moveable frame or trolley 54 that also carries a roll 56 of the resilient mat 50. As such, the second layer of membrane 46 functions as an adhesive which, because it is still liquid and the resilient mat 50 is pressed into it, will flow and enter surface irregularities, interstices and voids 51 in the resilient mat 50, intimately bonding it to the first layer of membrane 44.

The resilient mat 50 (and the roll 56 thereof) is preferably rubber and is, or is similar to, a product sold under the trademark Regupol 6010 for a type of impact sound acoustic underlayment manufactured by Regupol Pty. Ltd., Smeaton Grange, N.S.W. The resilient mat 50 may also be constituted of or include reclaimed rubber, ground rubber, virgin rubber, vinyl, polyvinylchloride or polyvinyl acetate preferably having approximately 40% air filled interstices or voids 51 by volume that has been formed into a continuous sheet that, for ease of handling and installation, is preferably four or six feet (1.219 or 1.829 meters) wide and is cut and rolled into rolls of, for example, fifty feet (15.24 meters) in length. It will be appreciated that the spring rate of the resilient mat 50 may be increased by reducing the volume of the air filled voids 51 to 30% or less or may be reduced by increasing the volume of the air filled voids 51 to 50% or more. Different materials and combinations thereof will also provide differing spring rates. The thickness of the resilient mat 50 may be varied from 6 millimeters (0.236 inches) or less to 12 millimeters (0.472 inches) or more, 8 millimeters (0.315 inches) having been found to be a widely useful, nominal thickness.

If desired, the resilient mat 50, in the same or various thicknesses, may be installed in additional layers depending upon protection, sound transfer, vibration dampening and load carrying requirements. To install multiple layers of the resilient mat 50, an additional layer of the thinner membrane layer 46 is applied to the upper surface of each previous layer of the resilient mat(s) 50 and an additional layer of resilient mat 50 is installed while the additional thinner membrane layer 46 is still liquid and pressed into intimate contact with the thinner membrane layer 46 on the upper surface of the previous layer of the resilient mat 50 by the cushioned roller 52 so that a portion of the additional thinner membrane layer 46 is forced into the voids and interstices of the resilient mat 50, as described above. If multiple layers of the resilient mat 50 are installed, care should be taken to stagger or offset the seams between adjacent resilient mats 50 of each layer.

Referring now to FIGS. 5, 6 and 7, after the bridge deck 14 is completely covered by the resilient mats 50, a second layer of primer 62 is sprayed onto the surface of the resilient mats 50 at a rate of 30 to 50 square feet per gallon (0.72 to 1.2 square meters per liter). When the second layer of primer 62 is only slightly tacky, a third layer of elastomeric membrane 64 of one of the materials previously listed is sprayed on the second layer of primer 62 to a thickness of approximately 30 to 50 mils and preferably about 40 mils.

After these steps, installation of the monolithic waterproofing product 40 is complete and the ballast 22, the ties 24 and the rails 26 of the railroad track 20 may all be installed or re-installed on the waterproofing product 40 on the bridge deck 14.

It will be appreciated that the monolithic waterproofing product 40 of the present invention provides numerous benefits. The waterproofing product 40, particularly because of the resilient mat(s) 50, is thicker than similar products and the resilient mats 50 may be applied, as noted above, in multiple layers. Such increased thickness is projected to provide better sound and vibration attenuation than competing products. The preferred resilient mat 50, described above, contains approximately 40% air filled voids or interstices which allow the membrane layers to penetrate the resilient mats 50 and achieve an intimate bond therewith. This stiffens the entire waterproofing product 40 and provides a mechanical lock with the resilient mats 50.

Additionally, because of the material and surface finish of the third and final layer of membrane 64, namely tough and stiffly resilient, which is also the result of the resilient mats 50, the ballast 22 will create small depressions or pits in the surface of the membrane 64 but will not puncture it. This action tends to hold the ballast 22 in place, thereby providing a more stable roadbed and generating less noise as trains pass. Finally, because of the ease of building up the various layers of the waterproofing product 40 and the speed and uniformity with which the resilient mats 50 are installed, not only is the final product better from the standpoints of strength, durability and resistance to water penetration but its total cost (material and installation) is also less than competing products.

The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention. 

1. A multiple layer waterproofing product for bridge decks comprising, in combination, a first primer layer adhered to a substrate, a first membrane layer thicker than said first primer layer adhered to said first primer layer, a second membrane layer adhered to said first membrane layer, a layer of resilient mat defining air filled voids and having a thickness of at least 6 mm adhered to said second membrane layer by flow of said second membrane layer into said voids, a second primer layer adhered to said resilient mat, and a third membrane layer thicker than said second primer layer adhered to said second primer layer.
 2. The multiple layer waterproofing product of claim 1 wherein said primer and membrane layers are one of polyurethane, polyurea, methyl methacrylate, a polyurethane hybrid, bitumen or an acrylic.
 3. The multiple layer waterproofing product of claim 1 wherein said resilient mat includes virgin rubber, reclaimed rubber, ground rubber, vinyl, polyvinylchloride or polyvinyl acetate.
 4. The multiple layer waterproofing product of claim 1 wherein said bridge deck is fabricated of wood, concrete or steel.
 5. The multiple layer waterproofing product of claim 1 wherein said resilient mat is disposed on such bridge deck in transverse or longitudinal, parallel panels.
 6. The multiple layer waterproofing product of claim 1 wherein said resilient mat is disposed on such bridge deck in transverse or longitudinal, parallel strips having a width of approximately four feet.
 7. The multiple layer waterproofing product of claim 1 further including a third membrane layer disposed on said layer of resilient mat and a second layer of resilient mat disposed on said third membrane layer, said third membrane layer and said second layer of resilient mat disposed between said layer of resilient mat and said second primer layer.
 8. A method of providing monolithic waterproof protection for a bridge deck, comprising the steps of; applying a first primer layer to such bridge deck, applying a first membrane layer thicker than said first primer layer to said first primer layer and allowing said first membrane layer to cure, applying a second membrane layer to said first membrane layer, applying at least one layer of a resilient mat containing air filled voids and having a thickness of at least 6 mm to said second membrane layer while said second membrane layer is liquid, applying a second primer layer to said resilient mat, and applying a third membrane layer thicker than said second primer layer to said second primer layer.
 9. The method of providing monolithic waterproof protection of claim 8 wherein said membrane layer applying steps are achieved by spraying.
 10. The method of providing monolithic waterproof protection of claim 8 wherein said first and said second primer layers are approximately 20 mils thick.
 11. The method of providing monolithic waterproof protection of claim 8 including the additional first step of cleaning such bridge deck by sand or metal shot blasting.
 12. The method of providing monolithic waterproof protection of claim 8 including the additional steps of applying an additional second membrane layer to said resilient mat layer and applying an additional layer of said resilient mat to said additional second membrane layer while said additional second membrane layer is liquid.
 13. The method of providing monolithic waterproof protection of claim 8 wherein said first primer layer is applied by spraying, squeegeeing or rolling.
 14. A multiple layer waterproofing product for bridge decks and similar structures comprising, in combination, a first membrane layer disposed on said bridge deck having a thickness of approximately 60 to 120 mils, a second membrane layer adhered to said first membrane layer, a layer of resilient mat defining air filled voids and having a thickness of from approximately 6 mm to 12 mm adhered to said second membrane layer by flow of said second membrane layer into said voids, a primer layer adhered to said resilient mat, and a third membrane layer thicker than said primer layer adhered to said primer layer having a thickness of approximately 30 to 50 mils.
 15. The multiple layer waterproofing product for bridge decks and similar structures of claim 14 wherein said resilient mat includes virgin rubber, reclaimed rubber, ground rubber, vinyl, polyvinylchloride or polyvinyl acetate and said air filled voids constitute approximately 40% by volume.
 16. The multiple layer waterproofing product for bridge decks and similar structures of claim 14 wherein said resilient mat is disposed on such bridge deck in transverse, parallel strips.
 17. The multiple layer waterproofing product for bridge decks and similar structures of claim 14 further including a third membrane layer disposed on said layer of resilient mat and a second layer of resilient mat disposed on said third membrane layer, said third membrane layer and said second layer of resilient mat disposed between said layer of resilient mat and said primer layer.
 18. The multiple layer waterproofing product for bridge decks and similar structures of claim 14 further including an additional primer layer disposed between said bridge deck and said first membrane layer.
 19. The method of providing monolithic waterproof protection for a bridge deck of claim 8 further including the step of applying pressure to said resilient mat containing air filled voids to cause a portion of said second membrane layer to flow into said voids of said resilient mat.
 20. The multiple layer waterproofing product for bridge decks and similar structures of claim 14 further including a primer layer adhered to such bridge deck and to which said first membrane layer is adhered. 